In the opening moments of an Orleans Parish murder trial, prosecutors said two men -- a father and son called Big Joe and Little Joe -- arrived at a Mid-City double to break up a fight between neighbors. They were gunned down there, side-by-side, in a hail of bullets.

Assistant District Attorney John Alford told the jury Wednesday morning that they'd be forced to grapple with the senselessness of the shooting that claimed the lives of 17-year-old Joseph Elliott and his father, 41-year-old Joseph Evans.

Sabrina Elliott, the 17-year-old's mother, and several relatives, young girls, lived in the same building as Butler and his girlfriend.

On Jan. 8, 2012, just after the Saints won a game, Butler and his girlfriend began fighting outside, prosecutors said Wednesday. The couple was allegedly arguing over T-shirts -- Butler had made some shirts, and he, the girlfriend and several friends disagreed over whether they should wear them or sell them.

Sabrina Elliott and the children watched from an upstairs window.

Butler's girlfriend reportedly began calling them names, and Elliott went outside to tell her not to talk to the children that way.

The two women began arguing, Alford said.

Butler, at some point, allegedly got out a gun and put it down on a table outside.

Elliott called her son, Joseph, 17. She asked him to come over with his father, told him she was fighting with a man who pulled a gun. The boy was known as "the reconciler," his friends have said, because he always tried to make peace. He once started a Sunday evening worship group for teens.

Butler allegedly heard Sabrina Elliott talking to him on the phone, and left to get another gun, Alford said.

Joseph Elliott and Joseph Evans, known as Big Joe and Little Joe, arrived.

They reportedly told the group to try and get along. They said they were neighbors, and would have to learn how to live next to each other. They said they'd take their people inside, and asked Butler to do the same.

The fight waned, but flared again, and the two women resumed yelling at each other.

Evans told everybody to go inside.

Butler, allegedly, pulled a 9mm handgun and fired a shot into the crowd.

But his gun jammed.

The Elliott family tried to take cover into their apartment -- the women and girls first, followed by the father and son.

Butler allegedly ran back into his apartment, switched the gun for another and returned.

He emptied his gun into the hallway, prosecutors said, shooting both men multiple times. Alford called it an "execution."

"That's where they died, right next to each other, in a pool of blood," said Alford, who is prosecuting the case with Lauren Favret before Orleans Parish Criminal District Court Judge Frank Marullo.

Prosecutors played a muffled 911 recording, where a little girl can be heard telling an operator that "Tabari" and another man named Joe shot her brother.

Butler's attorney, Don Donnelly, declined to give an opening statement to the jury.

Butler and a second man, 21-year-old Joseph Tate, were both arrested and charged with second-degree murder.

Tate pleaded guilty Monday to two counts of the reduced charge of accessory to second-degree murder. He is facing five years in prison on each count, and is scheduled to be sentenced on Thursday.